/t  M  ■    i  i]  ot  in 


Issued    November   25,    190i 


U.  S.  DEPARTMENT  OF  ACxRICULTURE, 

Bl  REAL1  (>F  PLANT  [NDUSTRY— Circular  No.  16. 
B.  T.  GALLOWAY,  Chli  i  ol  Bureau. 


A  NEW  BASIS  KOI!  BARLEY  VALUATION 
AM)  IMPROVEMENT. 


ALBERT  MANN. 
Expert  in  Charge  "i    Special  Barley    Investigations. 


!     Cir.  10     08 


US  DEPOSITORY 


BUREAU  OF  PLANT  INDUSTRY. 

Physiologist  and  Pathologist,  and  Chief  of  Bureau,  Beverly  T.  Galloway. 

Physiologist  and  Pathologist,  and  Assistant  Chief  of  Bureau,  Albert  F.  Woods. 

Laboratory  of  Plant  Pathology,  Erwin  F.  Smith.  Pathologist  in  Charge. 

Investigations  of  Diseases  of  Fruits,  Morton  B.  Waite,  Pathologist  in  Charge. 

Laboratory  of  Fortst  Pathology.  Haven  Metcalf,  Pathologist  in  Charge. 

Cotton  and   Truck  Diseases  and  Plant  Diseast  Survey,  William  A.  Orion.  Pathologist  in  Charge. 

Plant  Lift  History  Investigations,  Walter  T.  Swingle,  Physiologist  in  Charge. 

Cotton  Breeding  Investigations,  Archibald  D.  Shamel  and  Daniel  N.  Shoemaker,  Physiologists  in  Charge 

Tobacco  Investigations,  Archibald  D.  Shamel.  Wightman  W.  Garner  and  Ernest  11.  Mathewson,  in  Chargi 

Corn  Investigations,  Charles  P.  Hartley,  Physiologisl  in  charge. 

Alkali  mill  Drought  Resistant  Plant  Breeding    Investigations,  Thomas  II.  Kearney,   Physiologist  in 

Charge. 
Soil  Bacteriology  and  Water  Purification  Investigations,  Karl  K.  Kellerman,  Physiologisl  in  Charge 
Bionomic  Investigations  of  Tropical  and  Subtropical  Plants,  Orator  F.  Cook.  Bionomist  in  Charge. 
Drug  and  Poisonous  Plant  Investigations  and  Tea  Culture  Investigations,  Rodney  ll.  True,  Physiologisl  in 

Charge. 
Physical  Laboratory,  Lyman  J.  Briggs,  Physicist  in  Charge. 

crop  Technology  and  Fiber  Plant  Investigations,  Nathan  A.  Cobb,  Crop  Technologist  in  Charge. 
Taxonomic  and  Rangt  Investigations,  Frederick  V.  Covillc.  Botanist  in  Charge. 
Farm   Management  Investigations,  William  J.  Spillman,  Agriculturist  in  Chargi'. 
Grain  Investigations,  Mark  Alfred  Carle  ton,  Cerealist  in  Charge. 
Arlington  Experimental  Farm.  Lee  C.  Corbett,  Horticulturist  in  Charge. 
Vegetablt    fisting  Gardens.  William  W.  Tracy,  sr.,  Superintendent. 
Sugar-But  Investigations,  Charles  O.  Townsend.  Pathologist  in  Charge. 
II  estern  Agricultural  Extension  Investigations,  Carl  S.  Scofield,  Agriculturist  in  Charge. 
Dry-Land  Agriculture  Investigations,  E.  Charming  Chilcott.  Agriculturist  in  Charge 
Pomological  Collections,  Gustavus  B.  Brackett,  Pomologist  in  Charge. 

Field  Investigations  in  Pomology,  William  A.  Taylor  and  G.  Harold  Powell,  Pomologists  in  Charge. 
Experimental  Gardens  and  Grounds,  Edward  M.  Byrnes,  Superintendent. 
Fonigii  Seed  and  Plant  Introduction,  David  Fairchild.  Agricultural  Explorer  in  Charge. 
Forage  Crop  Investigations,  Charles  V.  Piper,  Agrostologist  in  Chargi 
Seed  Laboratory,  Edgar  Brown,  Botanist  in  Charge. 
Grain  Standardization.  John  D.  Shanahan.  Crop  Technologist  in  Charge. 
subtropical  Laboratory  and  Gardi  a .  Miami.  Fla..  P.  .1.  Wester,  Gardener  in  Charge 
Plant  Introduction  Garden,  Chico,  Co'.,  W.  W.  Tracy. jr.,  Assistant  Botanist  in  Charge 
South  Texas  Gardt  n .  Brownsx  illi .  Tex. ,  Edward  C.  Green,  Pomologist  in  Charge. 
Farmers'  Cooperative  Demonstration   lie/;..  Seaman  A.  Knapp,  Special  Agent  in  charge. 
Seed  Distribution  (directed  by  chief  of  Bureau),  I. isle  Morrison.  Assistant  in  General  Charge. 


Editor,  J.  E.  Rockwell, 
Chief  Clerk,  James  E.  Jones. 
i  it    16] 

2 


B.   P.  I.— 401. 


A  NEW  BASIS  FOR  BARLEY  VALUATION 
AND  IMPROVEMENT. 


INTRODUCTION. 

In  planning  for  the  improvement  of  barlej  crops  there  are  among 
many  other  things  two  of  great  importance:  (1)  The  means  of  clearly 
recognizing  the  best  grades  of  barley  and  (2)  the  knowledge  of  what 
factors  or  qualities  in  barley  ii  is  especially  desirable  to  improve. 

A  great  many  tests  for  distinguishing  different  grades  of  barlej 
have  been  in  use.  Of  these  the  simpler  ones,  and  therefore  those 
thai  should  l>e  most  useful,  have  not  been  found  to  be  reliable,  ('(in- 
clusions based  upon  such  external  signs  as  color,  fineness  and  wrin- 
kling of  hull,  smooth  or  toothed  condition  of  the  uerves,  long  or  shorl 
haired  basal  brush,  and  size  and  shape  of  grain  are  serviceable,  but 
have  proved  so  inaccurate  that  it  is  evident  the}  cannot  be  depended 
upon  as  a  basis  for  scientifically  accurate  conclusions.  'The  test 
made  h\  cutting  the  grain  across  so  as  to  see  the  relative  mealiness 
of  it>  starch  contents  i>  also  verj  unsatisfactory,  because  there  are 
two  different  hut  similar  appearing  states  of  glassiness,  one  that 
injures  the  malting  qualities  of  the  grain,  while  the  other  has  no  such 
effect.  Even  the  more  difficult  ami  expensive  chemical  analyses 
leave  much  t<>  he  desired.  For  example.  the\  indicate  the  percent- 
age of  nitrogen  contained  in  a  sample,  hut  distinguish  with  great 
difficulty  between  the  different  kinds  of  nitrogenous  contents;  and, 
what  is  --till  more  unfortunate,  though  the}  accurately  determine 
the  chemical  composition  of  a  given  sample  the\  have  no  testimony 
to  offer  showing  why  one  variety  has  more  of  a  certain  substance  than 
another,  where  the  dilferent  constituents  aie  located  in  the  grain,  or 
how  superior  grades  of  barlej  ma\  he  recognized  and  -till  better 
grades  developed.  Therefore,  although  chemical  analysis  in  barley 
determinations  is  indispensable,  there  is  greal  need  for  a  trustworthy 
si  met  ural  test . 

In  undertaking  the  improvement  of  American  barleys  the  Bureau 
of  Plant   [ndustry  therefore  decided  to  attempt  the  solution  of  some 

[Cir.  16] 


4  A  NEW   BASIS  FOR   BARLEY  VALUATION   AND   IMPROVEMENT. 

of  these  questions  along  new  lines.  Mr.  David  F  aire!  did  has  believed 
for  some  time  that  a  thorough  study  of  the  internal  structure  of  the 
barley  grain  should  afford  better  knowledge  than  that  hitherto 
secured  of  the  location  of  the  various  constituents  of  the  grain  and 
especially  of  the  location  within  the  grain  of  those  energies  that 
bring  about  the  changes  included  in  the  artificial  process  called  malt- 
ing and  the1  natural  process  called  germination.  The  valuable  dis- 
coveries made  by  Dr.  N.  A.  Cobb  in  his  morphological  studies  of 
wheat  a  strengthen  the  belief  that  the  functions  of  barley,  included 
in  its  malting  processes,  however  complicated,  are  referable  to  some 
structural  parts  as  their  source  and  are  correlated  with  deiinite 
organs.  The  writer  therefore  undertook  a  careful  study  of  the 
internal  mechanism  of  the  barley  grain  as  to  the  structural  changes 
that  take  place  during  its  successive  steps  in  malting. 

To  do  this,  modifications  in  laboratory  technique  have  had  to  be 
worked  out  and  methods  discovered  that  would  give  the  best  results 
in  killing,  fixing,  sectioning,  staining,  etc.,  this  refractory  material 
so  as  to  fit  it  for  microscopic  study.  The  object  of  this  article  is 
merely  to  give  a  brief  sketch  of  the  work  so  far  accomplished  and  to 
announce  a  new  basis  for  barley  valuation. 

The  first  task  undertaken  was  to  investigate  anew  the  work  per- 
formed by  the  different  parts  of  the  grain.  This  was  necessary 
because,  although  an  enormous  amount  of  study  lias  been  given  to 
this  subject,  there  is  no  unity  of  opinion  to  be  found  in  the  reports 
published.  To  take  an  example:  it  has  long  been  known  thai  the 
peculiar  part  of  the  embryo  barley  plant  called  the  scutellum  is  an 
absorbing  organ,  which  seizes  upon  the  food  supply  stored  in  the  resl 
of  the  grain  and  transfers  it  to  the  growing  parts,  the  young  root  sys- 
tem and  the  stem.  The  shape  and  position  of  this  organ  suggesl 
such  a  use  to  even  an  untrained  observer,  its  broad,  flat  surface  is 
pressed  close  against  the  large,  stored-up  mass  of  starch,  called  the 
endosperm,  which  forms  the  bulk  of  the  grain;  anil  when  germination, 
or  its  modified  form  called  malting,  has  been  going  on  for  three  or 
I'oui'  days  it  is  easy  to  see  that  the  starch  endosperm,  especially  that 
portion  lying  nearest  the  scutellum,  is  disappearing  and  that  at  the 
same  time  the  embryo  plant  has  commenced  growth.  It  is  evident 
that  the  scutellum  is  absorbing  the  starch  ami  transferring  it  to  the 
plant.  But  this  can  not  be  effected  without  certain  preliminary 
changes.  The  walls  of  the  starch-containing  cells  must  firsl  be  broken 
down  and  the  starch  grains  must  then  be  changed  into  a  liquid  state 
l>\  conversion  into  sugar,  dextrin,  or  some  such  soluble  correlative 
before  t  he  scutellum  can  absorb  this  supplj  and  convey  it  to  the  plant. 

a  Published  by  the  Department  of  Agriculture  of  New  Smith  Wales  under  the  title 
"  I  traversal  Nomenclature  of  Wheat." 
r.  101 


\    M-.w     BASIS    FOR    BARLEY    VALUATION     \M>    [MPROV]   MINI.  5 

Ii  i-  therefore  importanl  to  know  where  the  ferments  or  enzymes 
necessary  to  bring  about  these  changes  are  secreted.  Are  the}  the 
producl  of  tin'  scutellum,  making  it  thereby  not  onhj  an  absorbing 
l)ii t  a  secreting  organ  '  <  >r  are  thej  located  elsewhere?  This  i-  one  of 
the  questions  about  which  there  is  much  diversity  of  opinion.  Some 
investigators  bold  thai  the  necessary  enzymes,  diastase  and  cytase, 
;iii'  to  In'  found  in  tin1  cells  of  the  starch  endosperm  itself,  and  that  if. 
as  is  probable,  the  scutellum  also  secretes  these  enzymes  ii  is  supple- 
mentary to  the  stored-up  supph  of  the  starch  cells.  Other-  believe 
all  or  a  considerable  part  of  the  supph  is  secreted  1>\  the  cells  of  the 
aleuroD  layer,  which  invests  the  entire  starch  endosperm  excepl  ;it 
i  he  end  of  the  grain  occupied  by  the  plantlet.  Certain  authors  hold 
that  both  this  layer  and  the  scutellum  supph  these  ferments.  Ii 
was  such  discordanl  testimony  on  this  and  other  point-  that  made 
necessary  at  the  outsel  a  thorough  stud)  of  the  morphology  of  the 
barlej  grain  so  a-  to  fix,  a-  far  a-  possible,  the  location-  of  these 
import  ant   fund  ion-. 

These  investigations  have  proved  that  the  enzymes  already  men- 
tioned, the  diastatic  and  cytatic  starch  ferments,  are  wholly  the 
producl  of  t  he  scutellum  and  are  secreted  by  its  outer  la)  <•:■.  called  t  he 
epithelial  layer;  that  although  a  minute  t  race  of  t  hem  is  to  he  found  in 
the  starch  cell-  (as  in  ail  starch-containing  tissue),  it  plays  so  slight  a 
part  in  the  normal  -tarch  conversion  that  it  is  practically  negligible; 
that,  furthermore,  the  aleuron  layer  has  nothing  whatever  to  do  with 
this  process.  The  scutellum  can  therefore  he  called  the  "malting 
organ"  of  the  barley  grain  and  it>  epithelial  cells  the  "malting 
glands."  This  organ,  together  with  the  size  and  quality  of  the  endo- 
sperm, is  therefore  of  the  highest  importance  in  all  quegtions  concern- 
ing the  food  value,  malting  value,  ami  germinating  value  of  barle]  . 

I>\  a  comparative  study  of  this  important  organ  in  the  leading  vari- 
eties of  cultivated  barley,  it  was  soon  discovered  that  it>  shape 
varies  urreatl_\.  At  least  two  distinct  types  exist,  with  main  inter- 
mediate forms-  one  ver\  broad,  almost  circular  in  outline,  covering 
tlu1  lower  end  and  reaching  well  over  the  shoulders  of  the  grain  sei 
fig.  1);  the  other  narrow  .  elongated,  with  nearly  parallel  -ide-  and 
rounded  or  pointed  tip  (see  fig.  2).  The  broad  scutellum  i-  generally 
nearly  ilat  or  so  slightlj  convex  on  it-  inner  surface  that  it  lies  in  a 
shallow  depression  of  the  -larch  endosperm,  while  the  narrow  scutel- 
lum is  thick  and  tongue  shaped  and  is  sunken  quite  deep  into  the 
endosperm.  Compare  the  depression  shown  on  the  left  in  figure  I 
with  that  in  figure  '_':  also  tin'  two  scutellums. 

Corresponding  differences,  though  less  strongly  contrasted,  were 
found  to  exisl  in  the  size  and  shape  of  the  epithelial  cell-  clothing  the 
inner  surface  of  these  two  types  y^(  scutellum.     The  broad,  shallow 

16] 


6  A   NEW   BASIS  FOR  BARLEY   VALUATION    AND   IMPROVEMENT. 

form  has  decidedly  narrow  and  elongated  cells,  on  an  average  live  to 
six  times  as  long  as  broad;  those  of  the  other  type  are  shorter  and 
relatively  thicker,  averaging  three  to  four  times  as  long  as  broad.  It 
is  easy  to  understand  how  the  former  will  have  a  greater  secreting 
power  than  the  latter,  since  the  number  of  cell  units  in  a  given  space 
will  be  greater  without  any  loss  in  the  capacity  of  each  cell. 

A  fact  of  especial  importance  is  that  the  broad,  circular,  slightly 
convex  type  of  scutellum  having  long,  narrow  epithelial  cells  is 
found  to  be  characteristic  of  the  best  grades  of  malting  barley, 
while  the  narrow,  deep-sunken  type,  with  short  and  broad  epithelial 
cells,  is  characteristic  of  barley  inferior  for  malting  purposes.     A 


Fig.  1. — High-grade  Swedish  pedigree  barley.  Tin'  hulls  and  outer  membranes  have  been  mim\  ed  to 
show  the  ideal  form  of  scutellum.  Grain  on  the  right  entire;  on  the  left  with  the  scutellum  removed, 
leaving  a  broad,  shallow  depression;  scutellum  in  the  center,  seen  from  under  side.  Magnified 8 
diameters. 

good  example  of  1  his  fad  is  seen  in  figure  ■'!.  The  value  of  this  correla- 
tion is  twofold:  (1)  It  furnishes  a  means  of  recognizing  the  grade 
of  any  variety  of  barley  by  a  test  that  is  unquestionably  more  reliable 
than  the  external  earmarks  hitherto  relied  upon,  such  as  character 
of  the  hull,  basal  bristle,  shape  of  the  grain,  etc.  For  in  the  case  of 
these  external  tests  we  have  nothing  more  than  an  accidental  and 
somewhat  inconstant  coincidence  between  form  and  physiological 
quality,  while  in  the  case  of  the-scutellum  we  deal  with  a  strictly 
vital  correlation,  a  necessary  and  therefore  (ixed  relationship  between 
the  organ  and  the  malting  efficiency.  In  the  matter  of  its  use  the 
SCUtellum  tesl  is  almost  as  easy  as  the  above-mentioned  external 
[Clr.  16] 


A    NEW    BASIS    FOR    i;\l;U\    VAL1    \TI<>\'    AND   IMPROVEMENT.  i 

tests,  the  general  build  of  this  organ  being  easily  made  out  1>.\ 
merely  removing  the  outside  hull-  of  the  grain.  Tin-  is  readily 
done  even  when  the  barley  is  dry,  though  it  is  better  to  soak  the 
sample  for  a  fe\n  bours.  The  examination  of  the  epithelial  layer  is 
also  a  comparatively  simple  operation.  A  longitudinal  section  of  a 
well-soaked  grain,  freed  from  it-  hulls,  can  be  quickly  made  with  a 
razor  or  -harp  knife,  and  the  microscope  will  then  reveal  the  general 
form  of  this  important  glandular  tissue.  Of  course,  better  sections 
can  be  secured  with  a  microtome.  Some  of  the  new  freezing  micro- 
tomes are  not  >>nl\  cheap  hut  are  easilj  operated.  The  one  used  iu 
these  investigations  will  enable  a  grain  investigator  to  prepare 
excellent  sections  in  five  to  eight  minutes,  and  such  sections  give  a 


Pro.  2,    Low-grade  barley  sold  on  the  Milwaukee  market.    Crop  of  1907     The  hulls  and   outer 
membranes  have  been  removed  to  show  the  poor  form  of  scutellum.     Grain  on  the  right  entire; 
on  the  left  with  scutellum  removed,  leaving  a  narrow,  deep-sunken  depression;  scutellum  in  the 
n  from  under  side.    Magnified  8  diameters. 

far  better  image  of  the  starch  body  it-  texture,  mealiness,  glassi- 
ness,  etc.  than  the  crude  method  of  cross-cutting  the  grain  now 
practiced  l>\  grain  buyers  and  malt  experts. 

ll    i-  tO   he  -ceil   hv   the    foregoing    that     the   lir-t    e— eiltial   for  barley 

improvement  mentioned  at  the  head  of  this  article,  namely,  the 
mean-  of  recognizing  the  best  grades  of  barley,  is  supplied  by  the 
structural  differences  of  the  scutellum. 

The  -ccnnd  essential  mentioned,  a  knowledge  of  what  factor- 
in  barley  it  is  especially  desirable  to  imprcn  e,  is  also  closelj  connected 
with  the  function-  of  the  scutellum, for  evidently  an\  improvement 
in  malting  barley  must  include  an  improvement  in  the  malting  organ. 
Other  factor-  are  without  doubt  involved,  the  quality  of  the  starch 

[Cir.  U.] 


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^^^^™ 

8  A   NEW    BASIS   Fdi;    BARLEY   VALUATION    AND    [IMPROVEMENT. 

endosperm,  the  percentage  of  nitrogen,  etc,  as  well  as  some  very 
weighty  agricultural  considerations  having  to  do  with  yield,  stiffness 
of  'straw,  etc.     But  whatever  other  elements  of  quality  enter  into 

our  work  of  Ameri- 
can barley  improve- 
ment, the  scutellum, 
as  the  most  potential 
part  of  the  barley 
grain,  is  likely  to  he 
one. 

How  far  this  is  ca- 
pable of  modification 
is  at  present  unde- 
termined. But  the 
opinions  of  those  ex- 
perimenters in  grain 
breeding  both  here 
ami  in  Europe  who 
•have  been  consulted 
on  this  point  agree 
that  there  is  no  a 
priori  reason  why  this 
particular  form  of 
plant  structure  should 
not  be  as  plastic  and 
capable  of  improve- 
ment as  any  other. 
The  general  success  in 
plant  breeding,  ac- 
cording to  modern  methods,  leads  us  to  expect  that  in  our  work  of 
barley  improvement  now  going  on  at  St.  Anthony  Park,  Minn.,  we 
shall  secure   results  of  distinct  value  to  American  agriculture. 


Fig.3.— Malted  barlry  from  Pilsen,  Aus1  ria.  Thegrainon  the  right 
ha:  ill-  sprout  removed  to  show  the  ideal  form  of  scutellum. 
Magnified  S  diameters. 


Approved : 

James  Wilson, 

St  cretary  of  Agi  icultun  . 

Washington,  I).  ('..  September 24,  1908. 

[Cir.  10] 

o 


